misc/183727: [wlan] ENOBUFFS incorrectly returned when tx packet is deferred due to power management

Gavin Atkinson gavin at FreeBSD.org
Wed Nov 6 20:10:03 UTC 2013


>Number:         183727
>Category:       misc
>Synopsis:       [wlan] ENOBUFFS incorrectly returned when tx packet is deferred due to power management
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Nov 06 20:10:02 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Gavin Atkinson
>Release:        11-CURRENT
>Organization:
>Environment:
head r254082
>Description:
r254082 introduced a bug where outgoing packets that were not immediately transmitted but ended up being enqueued would still return ENOBUFFS to the caller.  This manifests itself for me (iwn, Intel 5100) as up to five "No buffer space available" messages while pinging an external host, almost exactly 300 seconds apart.  This seems to only happen when using 11n, and can be worked around by "ifconfig wlan0 -ht" or similar.

Instrumenting ieee80211_output.c shows that ENOBUFFS is being returned by the IEEE80211_NODE_PWR_MGT check in ieee80211_vap_pkt_send_dest().

It is believed (though not yet confirmed) that r257754 will fix this issue; this PR is to provide extra referenced information for the MFC.
>How-To-Repeat:
Attach to an 11n network, ping something remote.
>Fix:
r257754, hopefully.

>Release-Note:
>Audit-Trail:
>Unformatted:


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